This Multi-Purpose 4 lbs density half bolster is made out of Memory Foam which is a heat-sensitive foam pillow that supports immediately and responds to your body's shape, weight, and warmth. This half bolster molds to a custom cradle support for your head, back and legs. This pillow can be used while reading, sitting or simply relaxing to help ease leg fatigue while sleeping or lying on your back. You can take it with you to the beach or while hiking. Can be used in the car or the boat to relax your back.